Continued adding more comments about what each section/option does.

Continued adding more system info sections as needed for various components.
Enabled the welcome transform.

config/cloud.cfg

@@ -1,8 +1,26 @@
-user: ubuntu
-disable_root: 1
-preserve_hostname: False
+# The top level settings are used as transforms
+# and system configuration.
 
+# This user will have its passwd adjusted
+user: ubuntu
+
+# If this is set, 'root' will not be able to ssh in and they 
+# will get a message to login instead as the above $user
+disable_root: true
+
+# This will cause the set+update hostname module to not operate (if true)
+preserve_hostname: false
+
+# Example datasource config
+# datasource: 
+#    Ec2: 
+#      metadata_urls: [ 'blah.com' ]
+#      timeout: 5 # (defaults to 50 seconds)
+#      max_wait: 10 # (defaults to 120 seconds)
+
+# The transform modules that run in the 'init' stage
 cloud_init_modules:
+ - welcome
  - bootcmd
  - resizefs
  - set_hostname
@@ -12,6 +30,7 @@ cloud_init_modules:
  - rsyslog
  - ssh
 
+ # The transform modules that run in the 'config' stage
 cloud_config_modules:
  - mounts
  - ssh-import-id
@@ -30,6 +49,7 @@ cloud_config_modules:
  - runcmd
  - byobu
 
+# The transform modules that run in the 'final' stage
 cloud_final_modules:
  - rightscale_userdata
  - scripts-per-once
@@ -40,9 +60,15 @@ cloud_final_modules:
  - phone-home
  - final-message
 
+# System and/or distro specific settings
 system_info:
-   paths:
-      cloud_dir: /var/lib/cloud/
-      templates_dir: /etc/cloud/templates/
-      upstart_dir: /etc/init/
+   # This will affect which distro class gets used
    distro: ubuntu
+   # Other config here will be given to the distro class and/or path classes
+   paths:
+      cloud_dir: "/var/lib/cloud/"
+      templates_dir: "/etc/cloud/templates/"
+      upstart_dir: "/etc/init/"
+   package_mirror: "http://archive.ubuntu.com/ubuntu"
+   availability_zone_template: "http://%(zone)s.ec2.archive.ubuntu.com/ubuntu/"
+   ssh_svcname: ssh